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4.5 LEACHATE MONITORING The laboratory results for leachate monitoring well MW-2, are summarized in Table 3 and time-series concentration plots are presented in Appendix D. As shown on Table 3, no VOCs were measured in leachate monitoring well MW-2 during the first quarter 2007 monitoring period. 4.6 SURFACE-WATER MONITORING First quarter 2007 field and laboratory results for surface-water monitoring stations (SW-1, SW-2, and SW-3) are summarized in Table 4. Locations SW-1 and SW-2 are located upstream of the landfill within the Walker and French Camp Sloughs, respectively, and are used as background sampling points,while SW-3 is located downstream of the landfill at the confluence of the two sloughs. Water quality data from surface-water sampling stations were graphed on time-series concentration plots and are presented in Appendix D. For the surface water monitoring stations at the French Camp Landfill, CLs are used for the WQPS. The CLs shown in Table 4 were calculated by Herst&Associates using Sanitas®, a state-approved statistical software program using historical data from background surface water stations SW-1 and SW-2, and are presented in Appendix D. As shown in Table 4,with the exception of broodichloromethane,bromoform, and dibromochloromethane at background station S -2,no CL exceedances were noted during the first quarter 2007 monitoring period. During the fourth quarter 2006, similar concentrations of bromodichloromethane,bromoform, and dibromochloromethane were measured in QA/QC blanks at several landfills and an audit by BC indicated that the VOCs were the result of contaminated VOA containers. BC reported that they destroyed all of the contaminated VOA containers, however, a few VOA containers may have been missed. Given that SW-2 is a background surface water station and the recent laboratory contamination,it is unlikely that these VOCs are the result of an impact from the facility and further monitoring is necessary to evaluate the significance of these suspect VOCs. Trend analyses indicate that turbidity at surface water stations SW-1, SW-2, and SW-3 depict statistically significant increasing trends. Since turbidity exhibits a statistically significant increasing trend at background surface water stations SW-1 and SW-2, the increasing trend in turbidity at SW-3 is unlikely to be indicative of an impact from the facility. 5.0 SOIL-PORE GAS MONITORING During the current monitoring period, soil-pore gas samples were collected from probes SGP-2A, SGP-3, SGP-4A, SGP-5A, SGP-6A, SGP-7A, and SGP-8A on March 1,2007. However,upon receiving the samples, the lab noted that the 10-liter Tedlar bags for probes SGP-2A, SGP-6A, and SGP-7A were flat and these probes were resampled on March 5, 2007. In addition, since probe SGP-1 had been severed less than 1 foot below the ground surface, it was not sampled. Probe SGP-1 was abandoned and replaced with D:\2003_021\FC_w07.doc 5 Geologic Associates